This invention relates to metallurgical ladles commonly used to transfer, treat and pour molten metals, such as steel. It relates particularly to hoisting hooks used to lift and transfer molten metal from a furnace to ladle treatment position or a teeming position where the molten metal is poured into ingot molds or a continuous caster. The ladle is then lifted and moved to a pit where the ladle is inverted to dump residual slag and skull from the ladle into the pit.
Metallurgical ladles of the type used in the steel industry are large open top containers having a steel shell lined with refractory and a bottom pouring nozzle. A pair of trunnion pins are mounted on diametrically opposite sides of the steel shell to permit the ladle to be lifted easily in an upright position for transport and to be inverted 180.degree. to dump the slag and skull.
Apparatus for tilting and dumping metallurgical ladles consisting of bottom linkage is described in U.S. Pat. Nos. 2,881,488 and 3,550,816.
In recent years, steelmakers have increased the size of the ladles in a shop either to provide sufficient freeboard height for ladle treatment operations, such as reagent injection, or to accommodate increased furnace capacity. In many shops the lifting height of the ladle cranes to accommodate the larger ladles cannot be increased easily due to structural limitations in the shop building. The crane lifting height in the shop must be sufficient not only to allow the ladle to clear all objects in the path of its transport to the ladle treatment or teeming stations, but also to permit the ladle to be inverted over the pit while being dumped.